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The achromatic (1) dimension of colour, ranging from black (0) to white (10) in the Munsell value scale of lightness, being one of the three major dimensions of colour together with hue and saturation (1). It is the psychological counterpart of physical luminance, but the fact that it does not correspond in a simple way to physical light intensity can be demonstrated by first noting the lightness of a television screen when the power is turned off—it is usually not very dark—and then switching on the power and observing that parts of the picture appear much darker and even pitch black, despite the fact that the transmitted images can only increase and never reduce the intensity of the light coming from any part of the screen. Also called Munsell value or brightness, although brightness is specifically related to luminance, which as explained above is a different though closely related physical property. See also Gelb effect, Hering grey, Kardos effect.